Well first off the Nielsen Videoscan first alert still does not include Walmart sales so DVD sales are always more there, even now.

Plus seven days is the first week studio claim while the Nielsen Videoscan report has the new titles usually on Tuesday and ends on Sunday and the HMM revenue data ends on Saturday, so those are six or five day reporting after the Tuesday releases.

The trends will all be the same and general relationships with other titles but all the data sources we have differ in date ranges , covering Walmart or not and in their methods so magnitudes are always an issue.

We also had this conflict in the reporting as well for Immortals:

The Nielsen Videoscan first alert reported Blu-ray unit share was with Blu-ray 3D skus being 18.45% of OD sales.

Immortals Blu-ray 3D

58.82% of OD was Blu-ray
31.36% of Blu-ray was Blu-ray 3D
18.45% of OD was Blu-ray 3D

Quote:

20th Century Fox Home Entertainment has sold more than 1.2 million units of the action-fantasy film Immortals during its first week of release, the studio and Relativity Media announced March 16.

In a positive sign for high-def, 44% of retail disc sales were Blu-ray Disc, and the 3D Blu-ray combo pack accounted for 10%.